Effects Of Different Loading Doses Of Dexmedetomidine On Effect-site Concentration Of Propofol Given By Target-controlled Infusion

Objective To investigate the effects of intravenous infusion of different loading doses of dexmedetomidine on effect-site concentration of propofol by target-controlled infusion (TCI) with bispectral index (BIS) as the index of depth of anesthesia.Methods Sixty patients undergoing laparoscopic gynecologic surgery, ASA I or II, were randomly divided into three groups (n=20). Patients in the group D1, group D2 and group C were respectively administered with dexmedetomidine 0.3μg/kg,0.6μg/kg, or sodium chloride injection by micro-pumps in 10 minutes before anesthesia induction. The patients in the three groups were under same anesthesia induction and the propofol target plasma concentration was adjusted according to BIS. Propofol effect-site concentration and hemodynamic changes were recorded before drug using, before induction of anesthesia, immediately before and after tracheal intubation, before skin incision,30 min after skin incision, at the end of operation and after extubation. Recovery time and adverse reactions were also recorded.Results There was no difference among the there groups in anesthesia time and waking time (P>0.05). But the doses of propofol were significantly different (P<0.01), the group C, group D1 and group D2 were (8.4=s1.5), (6.0±1.0) and (4.8±1.1) mg·kg-1·h-1 The propofol effect-site concentration of group D1 and group D2 were lower than that in group C (P<0.01), and group D2 were lower than group D1 (P<0.05) during induction and maintenance of anesthesia. Compared with group C, MAP and HR fluctuations caused by tracheal intubation were well controlled in group D1 and group D2. There were four patients of group D2 occurred slowing in HR and had risen to an acceptable range after given atropine. There were no serious adverse reactions in the there groups.Conclusion The infusion of dexmedetomidine can make a reduction in propofol effect-site concentration to reduce the dosage of propofol. But as the dose increased, the incidence of intraoperative complications also increases accordingly.